Efficient signcryption without random oracles

Signcryption is an asymmetric cryptographic method that simultaneously provides confidentiality and authenticity at a lower computational and communication overhead. A number of signcryption schemes have been proposed in the literature, but they are only proven to be secure in the random oracle model. In this paper, under rational computational assumptions, we propose a signcryption scheme from pairings that is proven secure without random oracles. The scheme is also efficient and comparable to the state-of-the-art signcryption schemes from pairings that is secure in the random oracle model.